Gsm900/1800 Synthesizer Troubleshooting - Nokia 7600 Troubleshooting Manual

NMM-3
6-Troubleshooting

GSM900/1800 Synthesizer Troubleshooting

Pheonix Settings:
Band:GSM900/1800
Active unit:RX
Op Mode:Continuous
Rx Chan:37/700
AGC:maximum (default)
Yes
Probe VCO o/p
3769.6MHz GSM900
3685.6MHz GSM1800
Span 1MHz
RF Level=-10dBm
No
Yes
VCO output signal
<-10dBm?
No
Check output signal on
1GHz Span. Signal found
on correct frequency?
No
Check with meter VCO
control voltage
Vc=0V?
No
VCO control
voltage>4V
Yes
Replace
VCO
Page 6-22
Company Confidential
Yes
Synth
OK
Check Balun output
& VCO solder joints
OK?
Yes
Replace
VCO
Yes
Yes
Check VCO
Vcc=2.8v
No
Baseband
Troubleshooting
Yes
Check VCO loop
filter components
OK?
No
Replace faulty
components
Copyright  2003 Nokia Corporation
Company Confidential
CCS Technical Documentation
No
Replace faulty
components
Replace
VCO
Yes
Check synth serial
Interface on Helgo
Yes
Replace
VCO
No
Helgo
Troubleshooting
Issue 1 (11/2003)